1. Field of the Invention
The present invention relates generally to a camera lens assembly, and more particularly to a camera lens assembly mounted to a portable personal device, such as a cellular phone or a Personal Digital Assistant (PDA), and an autofocusing method therefor.
2. Description of the Related Art
In recent years, it has been possible to reduce the size and weight of a camera, which is a device that photographs a subject, by using a camera device, such as a Charge-Coupled Device (CCD) or a Complementary Metal-Oxide Semiconductor (CMOS) to capture an image of a subject. Accordingly, a camera lens assembly is mounted to a portable personal device, such as a cellular phone or a PDA, and enables a user of the portable personal device to conveniently photograph a subject. With the growth of technology for such a camera device, a portable personal device has encroached on the digital camera market.
Due to difficulties in reducing the size and weight of a lens assembly, there have been limitations in incorporating an optical zoom function into a compact and lightweight camera lens assembly. However, as the size of a lens is reduced and the precision of a lens driving apparatus is improved, the optical zoom function, an autofocusing function, and other camera functions are being incorporated into camera lens assemblies mounted to portable personal devices. Among others, the autofocusing function has gradually become an essential function for a camera lens assembly mounted to a portable personal device. The autofocusing function automatically adjusts the distance between a lens and a camera device according to a distance between the camera device and a subject, thereby allowing an image of the subject to be clearly projected onto an image plane.
In manufacturing a camera lens assembly, setting the distance between a lens and a camera device is a main factor determining the quality of the camera lens assembly. In other words, independent of the autofocusing function, a camera lens assembly including a camera device and a lens must be designed such that the distance between the lens and the camera device corresponds to the focal length of the lens when the assembly is initially driven.
Technology related to such initial focusing is disclosed in Korean Patent Registration No. 773,405, filed on Nov. 22, 2006 (hereinafter, '405). According to the '405 patent, an operator fixes the initial position of a lens through an initial focusing, in which the manufacture of a camera module is finished. Then, the finished camera module passes through a pre-delivery quality inspection for determining whether the initial focusing of the camera module was accurately performed, and then the camera module is delivered from the factory. With regard to this initial focusing and inspection, equipment, such as an index table, an adjustment unit, and a rotating unit driven by a cylinder, is required for the initial focusing, and particularly a module holder for facilitating the initial focusing is described in the above patent.
However, since the above-described conventional camera lens assembly process requires separate machinery (e.g. the module holder) for the initial focusing in the assembled state, the conventional camera lens assembly process has a disadvantage in that it requires a complex structure and expensive manufacturing equipment, such as an index table, an adjustment unit, and a rotating unit. Moreover, when the standard external dimension of a camera lens assembly is changed, a separate jig or holder must be manufactured accordingly, which increases costs. Furthermore, since an operator must manually perform focusing for each camera lens assembly, there is a disadvantage in that a large amount of time and labor are required for the manufacture of a camera lens assembly.